Advanced Materials Research Centre, Department of PG studies & Research in Physics, University Science College, Tumkur University, Tumkur 572103, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2011 Jan;78(1):64-9. doi: 10.1016/j.saa.2010.08.063. Epub 2010 Nov 12.
CaSiO3:Eu3+ (1-5 mol%) red emitting phosphors have been synthesized by a low-temperature solution combustion method. The phosphors have been well characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical spectroscopy. PXRD patterns reveal monoclinic CaSiO3 phase can be obtained at 900°C. The SEM micrographs show the crystallites with irregular shape, mostly angular. Upon 254 nm excitation, the phosphor show characteristic fluorescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 614 nm corresponding to 5D0→7F2 of Eu3+ ions, which is stronger than the magnetic dipole transition located at 593 nm corresponding to 5D0→7F1 of Eu3+ ions. Different pathways involved in emission process have been studied. Concentration quenching has been observed for Eu3+ concentration>4 mol%. UV-visible absorption shows an intense band at 240 nm in undoped and 270 nm in Eu3+ doped CaSiO3 which is attributed to oxygen to silicon (O-Si) ligand-to-metal charge-transfer (LMCT) band in the SiO3(2-) group. The optical energy band gap is widened with increase of Eu3+ ion dopant.
通过低温溶液燃烧法合成了 CaSiO3:Eu3+(1-5mol%)红色发射荧光粉。通过粉末 X 射线衍射(PXRD)、傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)和光学光谱对荧光粉进行了很好的表征。PXRD 图谱表明，在 900°C 时可以得到单斜 CaSiO3 相。SEM 显微照片显示，晶体具有不规则形状，大多呈角状。在 254nm 激发下，荧光粉显示出 Eu3+离子的特征荧光 5D0→7FJ(J=0,1,2,3,4)。电子跃迁位于 614nm，对应于 Eu3+离子的 5D0→7F2，比磁偶极跃迁位于 593nm，对应于 Eu3+离子的 5D0→7F1要强。研究了发射过程中涉及的不同途径。当 Eu3+浓度>4mol%时，观察到浓度猝灭。未掺杂的 CaSiO3 在 240nm 和 Eu3+掺杂的 CaSiO3 在 270nm 处有一个强烈的紫外-可见吸收带，这归因于 SiO3(2-)基团中的氧到硅(O-Si)配体到金属电荷转移(LMCT)带。随着 Eu3+离子掺杂剂的增加，光学能带隙变宽。
